Add EOS hostname and port values to which requests are forwarded if the
file is found in EOS. Add uplink hostname and port values to which
requests are forwarded if the file is not found in EOS. This is usually
a redirector up in the hierarchy.
Once we have some suitable physical file names constructed try to stat
them in order of their priority to check if the file is available. The
priority of a space token is increased if a lookup of a file in that
space is successful.